Y-Wing Sudoku Explained: Questions Beginners Ask
A Y-Wing is an advanced Sudoku elimination technique built from three bivalue cells that share candidates in a specific pattern. It allows you to remove a candidate digit from any cell that can 'see' both of the technique's outer cells, known as pincers. Think of it as a chain reaction that forces one outcome regardless of which path you take. This guide explains the logic, provides a clear example, and answers the most common questions beginners have about the [Y-Wing](/techniques/y-wing).
What is a Y-Wing?
A Y-Wing, sometimes called a 'Bent Triple', is a solving pattern involving exactly three cells. All three cells must each contain only two possible candidates (they are 'bivalue'). One cell, called the pivot, contains candidates A and B. The other two cells, called pincers, must each share one candidate with the pivot. So, one pincer contains A and C, and the other contains B and C. The key condition is that both pincer cells must be able to see the pivot cell (share a row, column, or block).
The logic works like a fork. If the pivot cell is A, then the A/C pincer cannot be A, so it must be C. If the pivot cell is B, then the B/C pincer cannot be B, so it must be C. In both possible scenarios, at least one of the pincer cells must be C. Therefore, any cell that can see *both* pincer cells cannot be C. This is the elimination you make.
A Y-Wing Example
Look at the cells R1C1 (pivot: 4,9), R1C9 (pincer 1: 4,1), and R9C1 (pincer 2: 9,1). The pivot has candidates (4,9). One pincer shares the 4 (so it is 4,1), and the other shares the 9 (so it is 9,1). The shared candidate between the pincers is 1.
Both pincers (R1C9 and R9C1) can see the pivot. Now, find a cell that can see both pincers. Cell R9C9 is in the same row as R9C1 and the same column as R1C9, so it sees both. Because at least one pincer must be a 1, cell R9C9 cannot be a 1. You can eliminate candidate 1 from R9C9. Notice the target cell (R9C9) does not need to see the pivot; it only needs to see both pincers.
How is a Y-Wing Different from an X-Wing?
While both are advanced pattern-based eliminations, they are structurally different. An X-Wing uses four cells forming the corners of a rectangle, all containing the same candidate, and eliminates that candidate from other cells in the shared rows and columns. It's a two-by-two pattern.
A Y-Wing uses three bivalue cells connected in a 'Y' shape. It eliminates a candidate that is *not* in the pivot cell (the 'C' candidate shared by the pincers). The Y-Wing's logic is based on a 'forcing chain' between three cells with three different candidate digits. It's often a more versatile pattern to spot after simpler techniques like Hidden Pairs are exhausted.
When Should You Look for a Y-Wing?
You should search for a Y-Wing when the puzzle has stalled after applying all basic techniques like Singles, Pairs, and Triples. The board will typically have several bivalue cells remaining. Start by scanning for potential pivot cells—cells with exactly two candidates. Then, check if there are two other bivalue cells that share one candidate each with the pivot and share a third candidate between themselves.
Practice is key. Our hint engine finds that players who actively look for the A/B, A/C, B/C pattern in bivalue cells start to recognize Y-Wings much faster. Don't get discouraged if you miss it; use the hint system to have it pointed out, which reinforces pattern recognition.
- Focus on bivalue cells as potential pivots.
- Check if the two pincer cells can both 'see' the pivot.
- Verify the pincers share a common candidate (C) that is not in the pivot.
Is the Y-Wing Technique for Beginners?
The Y-Wing is considered an advanced intermediate technique. Beginners should first master all basic strategies, including Naked and Hidden Singles, Pairs, and Triples. However, an ambitious beginner who understands bivalue cells and 'seeing' relationships can learn the Y-Wing logic. It's an excellent first step into the world of chaining and advanced logic.
Think of it as a bridge technique. It introduces the concept of a forcing chain (if this, then that) in a contained, three-cell package, which is foundational for even more advanced methods like XY-Chains and Swordfish.
What Does a Y-Wing Eliminate?
A Y-Wing eliminates one specific candidate digit (the 'C' digit shared by the two pincer cells) from any and all cells that have full visibility of both pincer cells. This target cell can be in the same row, column, or block as one pincer, and the same row, column, or block as the other pincer. The elimination is powerful because it can happen at a distance, connecting cells that aren't directly related through a single row, column, or block.
Key Facts
- ▪A Y-Wing is a Sudoku technique that uses three cells, each with only two possible numbers.
- ▪The three cells in a Y-Wing are called the pivot and two pincers, forming a specific candidate pattern.
- ▪The pivot cell contains candidates A and B. One pincer contains A and C, and the other contains B and C.
- ▪For the pattern to work, both pincer cells must be able to see the pivot cell (share a row, column, or block).
- ▪The logic forces at least one of the two pincer cells to be the digit C.
- ▪You can eliminate candidate C from any cell that can see both of the pincer cells.
- ▪The target cell for elimination does not need to see the original pivot cell, only both pincers.
- ▪A Y-Wing is different from an X-Wing, which uses four cells in a rectangle to eliminate a candidate.
- ▪Y-Wings are typically used after simpler techniques like Singles and Pairs no longer provide progress.
- ▪Mastering Y-Wing is a key step toward understanding more complex chaining strategies in Sudoku.
Frequently Asked Questions
What is a Y-Wing in Sudoku?
A Y-Wing is an advanced elimination technique using three bivalue cells in an A/B, A/C, B/C pattern. It eliminates candidate C from any cell that can see both the A/C and B/C pincer cells.
Y-Wing vs X-Wing: what's the difference?
An X-Wing uses four cells with one candidate. A Y-Wing uses three bivalue cells with three candidates. They use different logic and eliminate candidates in different ways.
When should I use the Y-Wing technique?
Use it when basic techniques fail and the grid has many bivalue cells. Look for the specific three-cell pattern where candidates are shared as A/B, A/C, and B/C.
Is Y-Wing a beginner technique?
No, it's intermediate. Beginners should master Singles, Pairs, and Triples first. Y-Wing is a great first advanced technique to learn after the basics.
What does a Y-Wing eliminate?
It eliminates the candidate shared by the two pincer cells (C) from any cell that sees both pincers. The target cell does not need to see the pivot.
Can a Y-Wing pivot have more than two candidates?
No. By definition, all three cells in a standard Y-Wing must be bivalue (have exactly two candidates each).